1. Field of Invention
The present invention relates to techniques for positioning and securing orthodontic brackets. More particularly, the present invention relates to a method for placing and securing orthodontic brackets utilizing an outside replica model of the patient's teeth for pre-positioning the brackets, followed by the transfer from the model to the patient's teeth, utilizing a two tray system for transferring the brackets, one of the trays being a soft tray and the other being a more rigid tray.
2. Prior Art
Positioning of dental or orthodontic mounting brackets of various types, known commonly as braces, on the teeth of a patient for correcting various irregularities is well known in the dental art. These brackets may be of several types. In most older work, entire bands were placed around the teeth, each band being equipped with a protuberance to which wires or bands could be attached in order to link the system of brackets and to allow proper correction of the patient's teeth. Other techniques include the use of brackets which are plates with attached protruberances which function as the previous bands but which are attached by cementing these brackets were needed to the face of the teeth, eliminating the need for bands encircling the teeth with the associated complications.
Also well known in the art is the use of models or dental casts made identical to the patient's teeth for determining the placing of the brackets. These casts are also used for other purposes known in the art.
The technique for placing brackets on teeth has been accomplished by individually placing brackets on the model and then removing them one at a time to be placed on the patient. It is also known in the art to use a single molded positioning cast to move the brackets as a unit from the dental cast to the patient's teeth.
In the latter technique, the brackets are first put on the dental cast. Next, a single positioner or "tray" is molded around the brackets and dental cast, so that, when the positioner is allowed to set and is removed, it also removes the brackets. This mold can then be put over the patient's teeth where they are cemented on. See U.S. Pat. No. 3,738,005 issued June 12, 1973 to Cohen et al.
The problem with the original tray system lies partially in the lack of flexibility in the system. The original tray had to be rigid enough to hold on to the teeth aiding in bracket placement. It also had to be flexible enough to fit over malposed teeth. This inconsistency was further exacerbated by the fact that the flexibility destroyed the assurance of accurate placement, since the original tray would become at least slightly distorted during placement of the tray over the teeth or even earlier when it is removed from the dental cast.
The problems caused due to the inherent flight between the two inconsistent goals of flexibility and rigidity were magnified by the fact that the process requires time for setting, and any deviation from the desired placement could cause potential doubling or worse of the time required to properly place the brackets. Or worse still, it could lead to the use of the improperly placed brackets in order to correct the patient's orthodontic problem with less than perfect results.
It is the goal of the present method to improve on the method for transferring brackets using a prepared carrier tray system from a dental cast or other arranging means to the patient's teeth.
It is also the goal of the present invention of make the profile of the cast lower, decreasing the bulk and hence increasing the ease with which the device is used by the treating physician and decreasing the discomfort of the patient and decreasing generally the time required for the entire operation.
It is also the goal of the present invention to allow a wider range of possible molding agents to be used than was consistent with the older methods in the art by decreasing the requirements put on the material used. This further allows the use of clear molding agents, allowing the treating physician to more closely follow the procedure.
It is also a goal to allow the use of more flexible primary trays, which actually contact the teeth to allow greater adjustment when the trays are actually in place.
It is also the goal of the present invention to provide a two tray, indirect bonding system for labial and lingual brackets, which is more easily used and less likely to cause mistakes and wasted time than the previously known single tray systems.
3. General Discussion of the Invention
As with the prior art, it is important that the patient be properly prepared before the brackets are implaced. In this invention, the preparation includes thoroughly cleaning the patients teeth, especially to ensure that there are no concretions or calculus build up on the teeth. It is important that no radical actions are taken which would result in a large change or movement of the teeth, such as by extraction of other teeth or separations of the teeth, between the time of making impressions and the time or seating of the indirect bonding trays. It is, however, one of the benefits of this system that it is more fit for for use where the normal and minor changes require some flexibility in the fitting of the trays over the malpositioned teeth.
Alginate impression are taken using procedures well known in the art. It is important that these impressions accurately reproduce the palate and all the tooth surfaces with clear definition of the gingival crest. Models are poured in these impressions, usually in yellow stone. Only these original models are acceptable due to the accuracy desired. Additionally, these models should be free of bubbles, chips, voids or other deformaties and should be trimmed if possible. The models are usually placed in a flat base so that accurate measurements may be made prior to the placement of the brackets on the model for later removal to the teeth.
At this point, the actual seating of the dental trays may be performed. The two tray procedure incorporates the advantage of allowing for the brackets and trays to be mounted on the dental cast either at the dental office or in another location.
The bonding system consists of two trays, one hard and the other soft as described in more detail below. The hard tray serves to hold the soft tray in its shape, after the soft tray is removed from the dental cast. The soft tray can be made in the same manner as the original mold for the dental cast, by pouring the soft tray material into containers which in turn is placed over the teeth or in this case the dental cast. The hard tray is made in such a manner as to hold the shape of the soft cast after it is in place.
Seating the trays is accomplished by preparing the patient in the manner used for direct bonding. First the teeth are pumiced, dried, etched, dried and sealed. It should be understood, of course, that other methods known in the art might be used.
Next a syringe is used to apply bonding material to the bracket base or the place on the teeth where the bracket base is to be set. The primary tray, described in detail below, is then placed in the patient's mouth. Due to the lack of rigidity necessary, the tray may be thin for easy and quick placing. It is usually suggested that the tray be placed buccally first, as it is the labial tray, preventing wiping of bonding material from the bases of the brackets. The secondary tray can then be immediately placed to insure proper seating without improper movement of the soft tray relative to the teeth.
The hard tray removes easily after the seating has occurred by the drying of the seating compound. The soft tray can then be removed, this being eased by the softness of the material involved.
The present invention provides a unique and improved method of transferring brackets from a prepared carrier tray system to the patient's teeth.
The advantage of the two tray system of the present invention over the previous one tray, indirect bonding system is that the previous original tray system had to be rigid enough to hold on to the teeth aiding in bracket placement. Since this tray had to be slightly flexible (to fit over malposed teeth) yet rigid enough to stay on the teeth, bracket placement to the patients teeth was not always accurate since the original tray would become slightly distorted during placement of the tray to the teeth.
The two tray system of the present invention virtually eliminates distortion during insertion of the trays into the mouth and over the teeth, which caused the brackets to be misplaced or drift from their ideal position on the patient's teeth.
The first tray is preferably made of a clear, thin, flexible material that retains its original shape after placing brackets to the teeth in their ideal position. A second tray is fabricated out of a very rigid, yet thin material and is molded over the first tray during the fabrication process, making the second tray a substantial, supplemental or complimentary duplicate of the first tray.
After the first (flexible) tray has been inserted into the patient's mouth over the teeth, the second (rigid) tray is inserted over the first tray. The second tray stabilizes the first tray and keeps it from moving and holds the brackets, which are temporarily fixed into the first tray, in their ideal position on the teeth until the adhesive bonding material cures and the brackets are secure to the patient's teeth. The second (rigid) tray is then removed. The first tray is then removed by easily peeling the soft flexible material away from the brackets and around the teeth. Since the brackets have been secured to the teeth with adhesive, the brackets will remain on the teeth.
The two tray, indirect bonding system of the present invention thus eliminates drifting of the brackets during insertion of the trays to the mouth and during the curing time required for the adhesive bonding material. Being preferably fabricated of clear materials, the trays allow the clinician a view of the teeth and of vital placement data, such as the clinical midline of the teeth. The trays are low in profile and fabricated out of a thin material, thus being very comfortable to the patient. The bracket-bearing, first tray is flexible enough to be peeled off the patient's teeth. Previous trays had to be cut off in sections, which was a very time-consuming procedure and could aid in pulling off the brackets accidentally. The invention's two tray system can be used to set brackets to the teeth labially or lingually. The trays can also be used as a vehicle for placement of the brackets and auxiliary attachments to all of the teeth from both the labial and lingual sides of the teeth simultaneously.